With a surging global population and seemingly endless urban growth, the world currently faces an imbalance of water types. Specifically, we have a shortage of clean drinking water and an excess of wastewater that requires treatment.
The processing of wastewater is typically done in three main ways. The best known is through a municipal system, which is what is present in most developed cities. The wastewater is carried from homes and businesses via a pipe that ultimately gathers the entire city's waste and carries it to a treatment facility, where the waste is removed and the water is rendered safe for discharge into a river or other body of water.
That process is essential because if it fails, the water being discharged can be very dangerous to humans, wildlife, and plants. That's why even though municipal wastewater has been processed for decades, there are still new and improving techniques being developed. Systems like dissolved air flotation, which prove far more efficient and effective than old, simple techniques, are in ever more widespread use each year.
The need for those systems is evident from the remaining two areas of wastewater treatment. The first of those is a smaller version of a municipal plant, processing waste for a group of homes that may be too close together for the final option.
That would be the familiar residential septic tank, which allows solids to settle in a large tank as the water level rises. Once it reaches a certain level, the water drains through a pipe that goes to a series of underground pipes called the leach bed. The leach bed is backfilled with gravel, and the pipes there have holes that gradually permit the water to soak in through the gravel.
Of course, it is an imperfect and incomplete system. The tank can finally have so much solid in it that it must be pumped out and the solid waste trucked to a municipal facility that processes it just like city waste. And if the homeowner does not have the tank pumped out in a timely fashion, the solids can drain out into the leach field and clog it up.
Another version of this includes an aerating tank that does a limited amount of processing to eliminate the need for a leach field.
The weaknesses of both of these techniques are clear. The primary problem with anything but the municipal system is that the effluent could potentially travel unchecked from the system into the environment. There is no monitoring done on a septic tank or aerator, only the attentiveness of the homeowner. Should the property change hands, the last known cleaning date can be lost and the system left unattended for too long.
In addition, the residential systems still require the use of municipal treatment facilities even when they are pumped in a timely fashion.
In order for clean water to be available for consumption and for wastewater to be treated in an economic and effective way, techniques like dissolved air flotation will need to come into ever-wider use. Their capabilities will not only improve existing municipal systems but will also increase the chances of an eventual conversion of outdated septic, aeration, and neighborhood-type systems that are too difficult to monitor and maintain, in addition to being inherently less effective.